Impact of Diabetes on Oncologic Outcome of Colorectal Cancer Patients: Colon vs. Rectal Cancer

Abstract

BackgroundTo evaluate the impact of diabetes on outcomes in colorectal cancer patients and to examine whether this association varies by the location of tumor (colon vs. rectum).Patients and methodsThis study includes 4,131 stage I-III colorectal cancer patients, treated between 1995 and 2007 (12.5% diabetic, 53% colon, 47% rectal) in South Korea. Cox proportional hazards modeling was used to determine the prognostic influence of DM on survival endpoints.ResultsColorectal cancer patients with DM had significantly worse disease-free survival (DFS) [hazard ratio (HR) 1.17, 95% confidence interval (CI): 1.00–1.37] compared with patients without DM. When considering colon and rectal cancer independently, DM was significantly associated with worse overall survival (OS) (HR: 1.46, 95% CI: 1.11–1.92), DFS (HR: 1.45, 95% CI: 1.15–1.84) and recurrence-free survival (RFS) (HR: 1.32, 95% CI: 0.98–1.76) in colon cancer patients. No association for OS, DFS or RFS was observed in rectal cancer patients. There was significant interaction of location of tumor (colon vs. rectal cancer) with DM on OS (P = 0.009) and DFS (P = 0.007).ConclusionsThis study suggests that DM negatively impacts survival outcomes of patients with colon cancer but not rectal cancer.

Metformin as an adjuvant treatment for cancer: a systematic review and meta-analysis

“…Previous studies have suggested that a diagnosis of DM has a negative impact on cancer outcomes [76, 77]; therefore, inclusion of non-DM patients in comparator groups could underestimate the beneficial effect of metformin. Owing to insufficient study numbers, it was only possible to analyse the effect of the presence or absence of non-DM patients in the comparator group for RFS in prostate cancer, where no evidence for an effect was found.…”

AACR Cancer Progress Report 2013

“…For example, type 2 diabetes has been reported to have a direct negative effect on tumor recurrence and survival in patients with colon cancer (60). In general, survival for cancer patients with type 2 diabetes is worse than for their nondiabetic counterparts because of indirect factors associated with diabetes.…”

Serum glucose and hemoglobin A1C levels at cancer diagnosis and disease outcome

“…Although bias might explain some of the associations, such as detection bias for bladder cancer (9) or reverse causality for pancreatic cancer, several large meta-analyses support the reproducibility of these observations (10,11). Additional studies showed higher mortality from colorectal (12,13), and breast cancers (14) among patients with diabetes, however the results were inconclusive and might not reflect cancer-specific mortality but rather mortality secondary to comorbidities associated with the metabolic syndrome (i.e. coronary artery disease), administration of less aggressive cancer treatment or difference in response to therapy in patients with diabetes (14-18).…”